Regenerative chimes



July 30, 1929. J. H. HAMMOND, JR

REGENERATIVE CHIMES Filed March 18, 1927 Patented July 30, 1929.

UNITED STATES JOHN HAYS HAMMOND, JR., GLOUCESTER, MASSACHUSETTS.

REGENERATIVE CHIMES. I

Application filed narch'is, 1927. Serial No. 176,387.

This invention relates to the production of musical sounds by regeneration.

The invention has particular reference to the improved control of decrement, whereby the sounds can be sustainedfor desired periods.

One feature of the invention relates to the provision of an improved pickup system for I the translation of energy in the form of electrical oscillations into compressional waves.

Another feature relates to the utilization of the electrical energy for controlling the emission of sound.

Another feature relates to the provision of improved means for setting into vibration a column of resonant material, thereby producing compressional waves in the surrounding medium.

Other objects will appear from the following description and claims taken in connection with the accompaning drawings in which there is shown in diagrammatic form a system for vibrating a series of chimes selectively', and for controlling regeneration.

Referring to the drawing, it will be seen that I have provided a plurality of chimes of which four are illustrated, as at 10, 11, 12, 13, each tuned to a note of the musical scale. The chimes are similar in construction, differing only in length, and thus in pitch of tone, and

it is thought that a description of one will suflice for all.

As shown each chime comprises a tube of resonant material, such as brass or the like. The tube is dependingly secured to a ring or cap 20, formed of paramagnetic material, and

snugly fitted ,to the respective tubenear itsupper end; Each cap is supported by flexible cords 21, shown two in number, fastened at their upper ends to a'wall of a substantially airtight wind chest 22. The wind chest 22 is mounted in fixed position on the frame (not shown) of the instrument, and there is.simi' larly secured thereto a stationary bar 23 opposite to and spaced apart from the chime tubes. For each tube, there is provided an arm 24, pivotally secured at one end to the bar 23 opposite the respective tube, and having at its other end a hammer 25, in the form of a ball of a hard material. A flexible strip 26, of soft leather or the like operatively interconnects each hammer 25 to one end of an operating arm 27 respectively, the other end of is provided a pneumatic 30, of conventional construction, mounted within the wind chest 22, which includes a movable element 31 pivotally connected to a thin rod 32 which slides snugly through an aperture in the lower wall of the wind chest, and through a suitably positioned hole in the respective operating arm 27. Two leather nuts 33 are secured to the rod 32, one below and the other above the operating rod 27. Each pneumatic 30 is controlled by a primary valve not shown. valves are of any well known construction, for example, of the type disclosed in Patent N 0. 1,323,530, to Wm. E. Haskell. Each primary is connected to a corresponding control conductor, there being one such conductor for each of the chimes 10, 11, 12 13, and designated by reference characters 34, 35, 36, 37 respectively. A common return conductor 38 is provided for connection to the opposite pole of all the primaries.

A source of pressure such as a supply pipe 40 leads to the interior of the wind chest 22, for supplying thereto air or other comprissible medium under pressure, whereby the pneumatics 30 may be collapsed when the respective primary valves are operated. This is accomplished when the electric conductor is connected in circuit, as will now be described.

For controlling the pneumatics there is provided a manual shown at 50, forming part of a console. The manual consists of a plu rality of keys 50, one for each note of the musical register which is to be played by the chimes. Each of the keys 51 is pivoted as at 52, and engages a metal strip 53, normally spaced from but in alignment with a contact spring 54. The metal strips 53 extend outwardly from a fixed conducting plate 55, which is mounted on and insulated from the frame of the console. The plate is connected by a common conductor 56 to one pole of a source of energy such as a battery 57 the other pole of which is connected to the common conductor 38 and thus to the primary valves of the pneumatics 30.- ,Each contact spring 54 is separately insulated, and is connected by one of the conductors 37, 36, 35, 34 to a corresponding primary valve, so that depression of one of the keys of the manual, causes a cor- Said responding one of the pneumatics 30 to collapse.

Adjacent the keys of the manual 50, there is provided a regeneration control handle 60, arranged to actuate a rotatable shaft 61 and a pair of spaced, toothed racks 62, 63'

operatively connected to the shaft 61 by means of pinions such as 64 keyed to the shaft and engaging the teeth of the racks. The racks are slidably mounted in keyways in spaced stationary brackets 65, 66. A transverse conducting bar 67 is mounted on the'racks 62, 63, and is provided with a plurality of brushes, such as 68, 69, 70, 71 carried thereby. A brush 72 is mounted on the left hand bracket 66 and is in sliding contact with one rack 62, thus forming an electrical connection with the brushes 68, 69, 70, 71. Each brush 68, 69, 70, 71 is in sliding contact with a variable resistance 73, 74, 75, 76 respectively, one terminal of each of which is connected as by a conductor 77, 78, 79, 80 respectively, to-a vacuum tube circuit. The vacuum tube circuits are similar and a description of'one will-suflice for all. For example, the conductor 80 extends to one terminal of condenser 81 and to a primary winding 82 of an auto transformer 83, a secondary winding 84 of which is connected through a blocking condenser 85 having a .high resistance 86 in shunt therewith, and

. to a grid 87 of a vacuum tube 88.

Each vacuum tube comprises an evacuated container having therein a filament 90 for emitting electrons, a plate 91 upon. which the electrons impinge, and the grid, 87 for controlling the passage of electrons. The filaments 90 of the vacuum tubes are con-s nected conventionally across afilament heatmg battery 92, one pole of whichis'connected as by a conductor 93 to the .brush 72, and

to the negative pole of a plate potential source such as a battery 94. The plates 91 of the vacuum tubes are connected to one terminal of the respective condensers 81 and by way of conductors such as 95, 96, 97, 98 to terminals of electromagnets 99, 100, 101, 102 respectively. The other terminals of the magnets are connected together and by way of a common conductor 103 to the positlve terminal ofthe plate potential battery 94. Acurrent thus flows through the windings of the electromagnets, and mag-' netic fields of magnets.

The magnets 99, 100, 101 and 102 are positioned so that their magnetic fields include the magnetic caps 20 of the chimes 10, 11, 12, and 13 respectively. The arrangement is such that movement of the cap with force are set up around these respect to the adjacent magnet produces in the magnetcoil, an electric current, and if the movement of the cap is periodic the current produced is correspondingly periodic and of like frequency. Furthermore when tuned, energy is impressed upon the chime to continue it in vibration at that frequency.

The circuit of each vacuum tube is preferably tuned to the frequency of the respective chime, by the employment of suitably characterized. condensers and inductances. The energy of the platecircuit of each tube is fed back to the grid circuit by the transformer 83. It will be noted that the winding 1 82 of the transformer 83 is shunted by the as sociated variable resistance, and that the amount of resistance in'circuit in adjustably controlled by the handle 60. The variable resistances are non-inductive, so as not to affect materially the tuning of the vacuum tube circuits when the handle 60 is turned.

In operation, the keys of the manual 50 are operated in accordance with the music to be played. When, for example, the forward end of the key 51 is depressed, the rear end is raised and the contact strip 53 is pushed into contact with the spring 54. A circuit is now closed from battery 57, conductor 56, conducting plate 55, contact strip .53,spring 54, conductor 37, winding of primary of pneumatic 30, conductor 38 to the opposite pole of the battery 57, energizing the inagnet and collapsing the pneumatic controlled thereby. The 'rod 32 and arm 27 are raised, bringing the ball 25 into sharp contact with the associated chime 13. The leather strip 26 has suflicient resiliency so that after having been brought sharply into contact with the chime tube, the ball 25 and the arm 24 on which it a is mounted will fallback slightly, so that the ball will rest out of contact with the chime tube while the pneumatic remains in its operated position.

The chime tube 13 having thus been struck, vibrates freely, emitting a series of compressional waves of a frequency corresponding 7 to the frequency to which the chime is tuned. These waves are impressed upon the surrounding medium and are conveyed thereby to the listeners, producing the effect of hell like musical tones. The natural decrement of these'waves is high, but may be modified as desired by turning the handle 60. In the position shown, a considerable portion of the resistance of the variable resistance is in circuit, and accordingly a considerable proportion of the energies of the plate circuits of the vacuum tubes are fed back to the grids.

As the chime tube 13 vibrates, the cap 20 thereof varies periodically the magnetic field former 83, battery 94, conductor 103, winding of electromagnet 102. An alternating electromotive force of like frequency is induced in the winding 84 of the transformer, and the potential of the grid 87 of the vacuum tube is accordingly varied. The flow of electrons from the filament to the plate is accordingly varied, and the change in space current causes a similar variation in the current through the winding of the electroma et 102, and a proportional periodic variation in the attractive efl'ect exerted by the magnet on the cap 20 of the chime tube. This energy is amplified by the action of the vacuum tube to a suflicient extent so that enough energy is imparted to the chime to continue it in vibration, so as to sustain the tone. The energy of any free oscillations produced in the vacuum tube circuit is insufficient to start the associated chim vibrating.

The amount of energy fed back to the grid of the vacuum tube may be conveniently varied by manipulation of the device 60, rotation of which in a counterclockwise direction moves the racks 62, 63 to the right of the drawing to increase the potentiometer resistance and thus increase the energy fed back. Rotation in a clockwise direction decreases the resistance and consequently the regenerative efiect.

In the description and claims, parts, characterlstic features and functions are identified by specific names for convenience of expression, but they are intended to be as generic in their application to similar parts or equivalent construction as the art will permit.

The invention upon which this application is based is broader than the specific embodiment shown and described forthe purpose of illustrating at least one of the ways in which it maybe employed. The scope of the invention is therefore to be understood as not being limited by the present specific description. I intend no liminations other than those imposed by the claims.

What is claimed is:

1. In a musical instrument, the combination withchimes tuned to notes of the musical scale, percussive means for impacting said chimes to produce musical sounds, a regenerative vacuum tube for each of said chimes for producing electrical oscillations of the frequency to which the respective chime is tuned,

and meansactivated by vibration of the respective chlme for rendering said tube efl'ective to impress oscillatory energy of like frequency upon said chime to continue the chime in vibration.

2. In a musical instrument, the combination with chimes tuned to notes of the musical scale, percussive means for impacting said u I chimes to produce muslcal sounds, a regeneraztive vacuum tube for each of said chimes for producing electrical oscillations of the frequency to which the respective chime is tuned,

activated by vibration of the respective chime for rendering said tube efiective to impress oscillatory energy of like frequency upon said chime to continue the chime in vibration, and means to modify the regenerative action of said tube.

3. In a musical instrument, the combination with chimes tuned to notes of the musical scale, percussive means for impacting said chimes to produce musical sounds, a regenerative vacuum tube for each of said chimes for producing electrical oscillations of the frequency to which the respective chime is tuned, activated by vibration of the respective chime for rendering said tube efiective to impress oscillatory energy of like frequency upon said chime to continue the chime in vibration, and a manually operable device to modify the regenerative action of said tube. 4. The combination with tuned elements for producing compressional waves, percussive means for impacting said elements to impress upon a natural medium waves of predetermined frequency, a regenerative circuit for each of said chimes for producing oscillatory energy of the frequency to which the respective chime is tuned, and means activated by vibration of the respective chime for rendering said circuit effective to impress the energy produced by said circuit upon the respective chime to sustain the compressional waves.

5. The combination of means for producing damped compressional waves, an oscillator for producing electrical oscillations of predetermined frequency, and means activated by vibration of the compressional wave producing means for rendering said oscillator effective to impress oscillatory energy upon said wave producing means to decrease the decrement of the waves produced thereby.

6. The combination of means for producing damped compressional waves, an oscillator' for producing electrical: oscillations of predetermined frequency, means activated by vibration of the compressional wave producing means for rendering said oscillator effective to impress oscillatory energy upon said wave producing means to decrease the decrement of the waves produced thereby, and means to modify the action of said last named means at the will of an o erator.

7. The combination 0 means for producing damped compressional waves, an oscillator for roducing electrical oscillations of predetermined frequency, means activated by vibration of the compressional wave producing means for rendering said oscillator effective to impress oscillatory energy upon said wave producing means to decrease the decrement of the waves produced thereby, and means to vary the action of said last named means at the will of an operator.

8. In a musical instrument, the combination with chimes tuned to notes of the musical scale, percussive means for impacting said bration of the respective chime for rendering chimes to produce musical sounds, a vacuum said tube effective to impress oscillatory en- 1 tube for each of said chimes, means for feedergy of like frequency upon said chime to coning back energy from the output to the input tinue the chime in vibration.

5 of each tube for producing electrical oscilla- Signed at Rome, in the Province of Rome tions of the'frequenq to which the respective and Kingdom of Italy, this second day of chime is tuned, variable resistance for con- March, A. D. 1927.. trolling the cue gy fed back, activated by vi- JOHN HAYS HANEMOND, JR. 

